1 /* 2 * kernel/ksysfs.c - sysfs attributes in /sys/kernel, which 3 * are not related to any other subsystem 4 * 5 * Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org> 6 * 7 * This file is release under the GPLv2 8 * 9 */ 10 11 #include <linux/config.h> 12 #include <linux/kobject.h> 13 #include <linux/string.h> 14 #include <linux/sysfs.h> 15 #include <linux/module.h> 16 #include <linux/init.h> 17 #include <linux/kexec.h> 18 19 #define KERNEL_ATTR_RO(_name) \ 20 static struct subsys_attribute _name##_attr = __ATTR_RO(_name) 21 22 #define KERNEL_ATTR_RW(_name) \ 23 static struct subsys_attribute _name##_attr = \ 24 __ATTR(_name, 0644, _name##_show, _name##_store) 25 26 #if defined(CONFIG_HOTPLUG) && defined(CONFIG_NET) 27 /* current uevent sequence number */ 28 static ssize_t uevent_seqnum_show(struct subsystem *subsys, char *page) 29 { 30 return sprintf(page, "%llu\n", (unsigned long long)uevent_seqnum); 31 } 32 KERNEL_ATTR_RO(uevent_seqnum); 33 34 /* uevent helper program, used during early boo */ 35 static ssize_t uevent_helper_show(struct subsystem *subsys, char *page) 36 { 37 return sprintf(page, "%s\n", uevent_helper); 38 } 39 static ssize_t uevent_helper_store(struct subsystem *subsys, const char *page, size_t count) 40 { 41 if (count+1 > UEVENT_HELPER_PATH_LEN) 42 return -ENOENT; 43 memcpy(uevent_helper, page, count); 44 uevent_helper[count] = '\0'; 45 if (count && uevent_helper[count-1] == '\n') 46 uevent_helper[count-1] = '\0'; 47 return count; 48 } 49 KERNEL_ATTR_RW(uevent_helper); 50 #endif 51 52 #ifdef CONFIG_KEXEC 53 static ssize_t kexec_loaded_show(struct subsystem *subsys, char *page) 54 { 55 return sprintf(page, "%d\n", !!kexec_image); 56 } 57 KERNEL_ATTR_RO(kexec_loaded); 58 59 static ssize_t kexec_crash_loaded_show(struct subsystem *subsys, char *page) 60 { 61 return sprintf(page, "%d\n", !!kexec_crash_image); 62 } 63 KERNEL_ATTR_RO(kexec_crash_loaded); 64 #endif /* CONFIG_KEXEC */ 65 66 decl_subsys(kernel, NULL, NULL); 67 EXPORT_SYMBOL_GPL(kernel_subsys); 68 69 static struct attribute * kernel_attrs[] = { 70 #if defined(CONFIG_HOTPLUG) && defined(CONFIG_NET) 71 &uevent_seqnum_attr.attr, 72 &uevent_helper_attr.attr, 73 #endif 74 #ifdef CONFIG_KEXEC 75 &kexec_loaded_attr.attr, 76 &kexec_crash_loaded_attr.attr, 77 #endif 78 NULL 79 }; 80 81 static struct attribute_group kernel_attr_group = { 82 .attrs = kernel_attrs, 83 }; 84 85 static int __init ksysfs_init(void) 86 { 87 int error = subsystem_register(&kernel_subsys); 88 if (!error) 89 error = sysfs_create_group(&kernel_subsys.kset.kobj, 90 &kernel_attr_group); 91 92 return error; 93 } 94 95 core_initcall(ksysfs_init); 96